Strip-feeding mechanism for motion-picture projectors and the like

ABSTRACT

A continuously rotating shaft carries a shutter which interrupts a beam of light, trained upon a perforated film in a motionpicture projector, several times per revolution. The shaft also carries a transport cam and an engaging cam coacting with a claw carrier forming a part of a film-feeding mechanism, the claw carrier having a tooth adapted to enter a perforation of the film whenever a cam follower co-operating with the engaging cam encounters a dwell of the latter. The transport cam has several peripherally spaced camming formations which, through a cam follower on the claw carrier, cause a limited entrainment of the film by the perforation-engaging claw tooth. The positions of the camming formations on the transport cam are so correlated with the shutter position that the resulting transport strokes coincide with different beam-interrupting phases in the course of a shaft revolution. With the aid of selective control means, the engaging cam is made inoperative during all but one of these beam-interrupting phases so that the transport cam is effective only once per revolution to entrain the film. The camming formations may be flanks of one or more peripheral humps of the transport cam differing either in their effective height or in the direction of their slope. In the first instance, operation of the control means enables selection of different film speeds; in the second instance a switchover between forward and reverse feeding is possible.

United States Patent Morell et al.

[75] Inventors: Josef Morell; Johann Nowak, both of Vienna, Austria [73] Assignees: Karl Vockenhuber; Raimund Hauser, both of Vienna, Austria 1 Filed: Jan. 24, 1973 1 11 Appl. No; 326,444

[30] Foreign Application Priority Data Feb. 1, 1972 Austria 797/72 June 2, 1972 Aust i 4784/72 [52] U5. C1. 352/79; 352/194; 226/64 [51 1 Int. Cl. G03b 1/22 [58] Field of Search 352/79, 80, 194, 195, 196, 352/191; 226/64, 65, 66

[56] References Cited UNITED STATES PATENTS 3,427,101 2/1969 Jorgensen et al. 352/194 X 3,449,044 6/1969 Caprio 352/194 3,460,730 8/1969 Krumbein 352/80 X 3,514,196 5/1970 Roman 226/65 X 3,537,629 11/1970 Riedel 226/64 3,556,649 1/1971 Nupnau 352/194 3,635,548 1/1972 Thomsen et a1. 352/79 3,637,125 l/1972 Freudenschuss.. 352/194 3,640,441 2/1972 Keznickl 352/195 3,775,000 1l/l973 Krob 352/79 FOREIGN PATENTS OR APPLICATIONS 2,049,854 4/1971 Germany 352/79 ILA [ 1 Sept. 23, 1975 Primary E.\'anzinerSamuel S. Matthews Attorney, Agent, or Firm-Ernest G. Montague; Karl F. Ross; Herbert Dubno I 5 7 1 ABSTRACT A continuously rotating shaft carries a shutter which interrupts a beam of light, trained upon a perforated film in a motion-picture projector, several times per revolution. The shaft also carries a transport cam and an engaging cam coacting with a claw carrier forming a part of a film-feeding mechanism, the claw carrier having a tooth adapted to enter a perforation of the film whenever a cam follower co-operating with the engaging cam encounters a dwell of the latter. The transport cam has several peripherally spaced camming formations which, through a cam follower on the claw carrier, cause a limited entrainment of the film by the perforation-engaging claw tooth. The positions of the camming formations on the transport cam are so correlated with the shutter position that the resulting transport strokes coincide with different beaminterrupting phases in the course of a shaft revolution. With the aid of selective control means, the engaging cam is made inoperative during all but one of these beam-interrupting phases so that the transport cam is effective only once per revolution to entrain the film. The camming formations may be flanks of one or more peripheral humps of the transport cam differing either in their effective height or in the direction of their slope. In the first instance, operation of the control means enables selection of different film speeds; in the second instance a switchover between forward and reverse feeding is possible.

10 Claims, 12 Drawing Figures US Patent Sept. 23,1975 Sheet 1 of4 3,907,413

FIG. lc

US Patent Sept. 23,1975 Sheet 2 of 4 3,907,413

US Patent Sept. 23,1975 Sheet 3 of4 3,907,413

FIG]

US Patent Sept. 23,1975 Sheet 4 0f 4 3,907,413

PIC-7.9

STRIP-FEEDING MECHANISM FOR MOTION-PICTURE PROJECTORS AND THE LIKE Our present invention relates to a strip-feeding mechanism for an optical recording or reproducing apparatus, more particularly a motion-picture projector, including optical equipment adapted to scan an intermittently advancing film strip provided with a row of longitudinally equispaced perforations, the advance of the film taking place during recurrent off-periods of a source of intermittent illumination for the film strip. Such a source of illumination is usually a rotating shutter, via a stroboscopically flashing lamp could also be used for this purpose.

The general object of our invention is to provide a simple and compact strip-feeding mechanism of this character having means for selectively switching among two or more modes of film transport which differ either in the length or in the direction of the transport stroke.

A more particular object is to provide a mechanism of this type in a motion-picture projector designed to accommodate different kinds of film, such as those of Super-8 and Standard-8 format.

We realize these objects, in accordance with the present invention, by providing first and second cam means mounted for joint rotation, advantageously about a common axis, in synchronized relationship with a source of intermittent illumination as defined above, each revolution of the two cam means coinciding with a plurality of off-periods of that source. A film strip, guided along a predetermined path and which may lie in a plane generally perpendicular to the axis of cam rotation, is normally disengaged from but periodically engageable by feed means for intermittent entrainment, the feed means being displaceable by the first cam means in a transport direction (substantially parallel to the guidepath of the strip) and by the second cam means in a perforation-engaging direction (generally transverse to that guidepath). The first cam means,

which may be a disk-shaped body centered on the axis of rotation, is provided for this purpose with a plurality of transport formations at peripherally spaced locations for coacting with the feed means during different offperiods in the course of a revolution; the second cam means is provided with one or more engaging formations positioned for coacting with the feed means during any of these different off-periods to enable entrainment of the film strip by only one transport formation selected with the aid of control means operatively engageable with one of these cam means preferably the second one during all but one of the off periods occurring in the course of one revolution.

In accordance with an important feature of our invention, the several transport formations are of mutually different configurations to enable selection of the aforementioned different modes of film transport. Thus, they may be constituted by similarly sloping flanks of a plurality of peripheral humps of the cam body, these flanks differing in height from one another so as to produce transport strokes of different lengths. They could, however, also be oppositely sloping flanks of a single hump enabling the film to be selectively transported in a forward or in a reverse direction.

In a preferred construction, the feed means comprises a claw carrier swingable about a pivotal axis substantially parallel to the film plane and shiftable in the direction of this axis, the second cam means then comprising an annular member and force-transmitting means coacting with one or more details on that member for swinging the claw carrier in its perforationengaging direction. The control means for the changeover among the different transport modes may be operatively coupled with the second cam means for bringing about a relative angular displacement of the annular member and the force-transmitting means e. g. a cam follower on an arm interposed between this member and the claw carrier by an angular distance corresponding to the angular spacing of the sloping hump flanks on the cam body coaxial with that member. Alternatively, the annular member may form a plurality of annular cam tracks provided with respective dwells, the force-transmitting means being selectively alignable by the control means with any one of these cam tracks.

Instead of relatively displacing an annular cam member and an associated cam follower acting as a forcetransmitting means, the control means could comprise an inhibitor selectively synchronizable with the source of intermittent illumination to block the swinging of the claw carrier in all but one off-period in the course of a revolution. Such an inhibitor may operate electromagnetically or mechanically as more fully described hereinafter.

The above and other features of our invention will now be described in detail with reference to the accompanying drawing in which:

FIGS. la, lb and 1c are a set of graphs respectively showing the profile of a transport cam, the profile of an engaging cam and the off-periods of a shutter in a stripfeeding mechanism according to our invention;

FIG. 2 is a face view of an embodiment of the invention with cams and a shutter conforming to the above graphs;

FIG. 2A is a side view of the mechanism substantially as seen on the line IIA IIA of FIG. 2;

FIGS. 3 and 4 are face views similar to FIG. 2, showing different modifications;

FIG. 5 is a side view of mechanism representing a further modification;

FIG. 6 is a face view similar to FIGS. 2 4, illustrating still another embodiment;

FIG. 7 is a set of graphs relating to the embodiment of FIG. 6;

FIG. 8 is a view similar to FIG. 6, showing yet a further embodiment; and

FIG. 9 is a set of graphs relating to the embodiment of FIG. 8.

According to FIG. la the profile of a transport cam includes a hump a for advancing a first film format, for example a Super-8 film, and a hump b for another film format, for example a Standard-8 film. These two transport movements coincide with respective lightinterrupting phases 8a, 8b (FIG. 1e). In order to let alternately one or the other transport stroke become effective, the engaging stroke is selectively correlated with the hump a or onto the hump b.

FIGS. 2 and 2A show a film-feeding mechanism operating in this manner. Films 1 of different perforation pitch are transported by a claw tooth 2 situated on a carrier 3. The carrier 3 is rectilinearly guided by means of balls 4 and is moreover swingable about an axis A passing through the balls 4. The carrier 3 bears a cam follower 5 which co-operates with a transport cam 7 seated on a drive shaft 6. On the shaft 6 there is further arranged a shutter 8 with three lobes or vanes 9, 10, 11. Also mounted on this shaft 6, concentrically with the transport cam 7, is an engaging cam whose disk-shaped body 106 forms two concentric cam tracks 12, 13. With these cam tracks 12, 13 a cam follower 14 is selectively alignable, acting as a force-transmitting means between the respective cam track and the carrier 3 which presses the cam follower 14 onto the face of the cam disk 100 under the action of a spring not shown. Vanes 9, 10 and 11 respectively produce the three offperiods 8a, 8b, 80 shown in FIG. 10.

The transport cam 7 has the profile shown in FIG. 1a, i.e. a first peripheral hump a effective over an angle a and a second peripheral huinp b effective over an angle B as seen from shaft axis 0. The cam follower 5 comes into the range of the angle a as soon as the vane 9 covers an image frame of the film 1. Thus, hump a is correlated with the light-interrupting phase or off-period caused by the shutter vane 9. It will also be seen that within the angular range of the shutter vane 9 the cam track 13 has a raised section or dwell 15 adapted to coact with cam follower 14 to cause engagement of claw 2 with film 1 coincident with the transport stroke of hump a as will be apparent from FIG. lb. Similarly, a raised section or dwell 16 on cam track 12 may coact with cam follower 14 to bring about such engagement coincident with the transport stroke of hump b as also seen in FIG. lb. This raised section 16 lies in the angu lar range of the shutter vane 10.

The cam follower 14 is shiftable from one cam track to the other by means of a control lever 17 which may be coupled with a changeover means for the film.

Although this embodiment is limited to a changeover between two different film formats, it is evident that for a given number of light-interrupting phases per revolution of the shaft 6 also a corresponding number of different transport movements may be provided.

For the assignment of the engaging stroke to different transport movements it is not essential to have a corresponding number of engaging cams or tracks. The curve form for the various engaging strokes is always the same, so that it suffices to effectuate a corresponding phase shift of this engaging stroke. Thus, a single cam follower could be shiftable by a corresponding angle along a single cam track to execute an engaging stroke. Such an embodiment is illustrated in FIG. 3 where corresponding elements bear the same reference numerals as in FIGS. 2 and 2A. Here again a transport cam 7 with two film-advancing humps is provided on the shaft 6, disk 100 having but one annular track 18 with a raised section or dwell 19 causing the engaging movement of track 2. The cam follower 14 cooperating with this cam track 18 is seated on a control arm 20 which is swingable about the shaft 6 and bears an operating lever 21 for format switching. The effective switchover of dwell 19 from one to the other hump of the transport cam 6 is carried out by swinging the op- 4 trated in FIG. 4 where a single cam track 22 differs from the cam track 18 of FIG. 3 in that instead of the raised section 19 there is provided a depressed dwell 23. Thus, a carrier 24 for the claw tooth 2 has an extension beyond the pivotal axis passing through the balls 4, this extension overlying two cam followers 25, 26. The cam followers 25, 26 are arranged on a bell-crank lever 27 which serves for the changeover from one film format to the other. Depending on the position of lever 27, one of the cam followers 25, 26 comes into register with the cam track 22 and controls the engaging stroke of the claw tooth 2. The two cam followers have an angular distance of 120 with respect to the axis of shaft 6, corresponding to the angular spacing of the shutter vanes 9, 10, 11 from one another. Such a construction not only simplifies the cam design and minimizes the swing of control lever 27, but also makes the engagement of the claw tooth 2 dependent only on spring tension so that the claw cannot perforate the film edge upon wrong threading of the film 2.

In some instances it may be difficult to install the control means for the switchover in the space beside the cams. For this case we propose a construction according to FIG. 5. Here, again, equivalent elements bear the same reference numerals'as before. In this embodiment the transport cam 7 is broader than would be necessary merely for the control of the claw carrier 3. The cam follower 5 engaging the transport cam 7 is designed as a small bar.

The engaging stroke of the claw tooth 2 is controlled by a cam disk a having a track 18, 19 similar to that of FIG. 3, disk 1000 being axially separated from the transport cam 7. Therefore a cam follower 29 is provided which is axially displaceable in a stationary guide 28.

The cam disk 106a is axially movable on the shaft 6 but is coupled with it for joint rotation by means of a helical rib 30 radially projecting from the shaft 6 over an angular range which corresponds to the relative offset of the two humps of the transport cam 7.

For the changeover of the claw stroke from one for mat to the other it is only necessary to displace the shaft 6 in the direction of the arrow 31. Stationary guides 32, 33 prevent the cam disk 100a from following this axial displacement. Owing to the helical shape of the rib 30, however, the cam disk turns through the desired angle upon displacement of the shaft 6 so that the relative timing of the engaging stroke and of the transport stroke is changed. The engaging stroke can thus be correlated with the transport stroke a or B (FIG. 10) of hump a or b.

If a changeover among more than two film formats is desired, handle 27 of FIG. 4 bearing the cam followers 25, 26 may have several arms and may be swingable as well as shiftable in the plane of the cam track 22. In the embodiments according to FIGS. 3 and 5 we may also provide additional engaging cams for changing over to further film formats. In this case the control means may include a mode selector for changing from one engaging cam to the other. In the embodiment of FIG. 3 it is not always necessary to mount the control lever 21 on the shaft 6. This type of assembly is required only when there is little space left around the cam track for the swing of the cam follower 14 upon changeover. Otherwise it is also possible to arrange the lever 21 eccentrically to the shaft 6 and outside the range of the cams, e.g. as shown in FIG. 8 described below.

FIG. 6 shows a further embodiment with elements similar to those of the preceding figures designated by the same reference numerals. These elements need therefore bedescribed only briefly.

The three-bladed shutter 8 and the associated cam disk 100 are fastened to the driving shaft 6. The cam disk forms a transport cam 7 with two humps a, b and an engaging cam track 106 with dwells 106, 106 represented by depressions as in FIG. 4. Opposite the cam disk lies the claw-carrying frame 3, which again is vertically shiftable and swingable about a pivotal axis defined by the two balls 4. The claw frame 3 has two filmengaging teeth 110, 111 which cooperate with the perforations of the film 1 and advance same according to the transport movement of the claw frame.

On the claw frame 3 there is provided the cam follower 5, here serving also as a force-transmitting means between the frame 3 and the disk 100, which is pressed against the periphery of the transport cam 7 under the action of a spring 114 and onto the face of engaging cam 106 under the action of a spring, not shown, which acts axially upon this bar-shaped cam follower.

The claw frame 3, consisting of ferromagnetic material, confronts a pot-shaped magnet 116 which is peri odically energized by a pulse generator 117. To the extent so far described, the system of FIG. 6 generally corresponds to that of commonly owned U.S. Pat. No. 3,637,125 to Otto Freudenschuss, except for the presence of the two dwells 106', 106" and the two humps a, b.

As clearly illustrated in FIG. 7, the profile of transport cam 7 is the same as in FIG. 1a with its humps a, b having active flanks of different height in a pair of angular ranges or and B. In the range a the transport stroke is larger, e.g. as required for Super-8 films, and in the range [3 the stroke is smaller as needed, for example, for Standard-8 films. To each of these two humps of the transport cam 7 there is assigned one of the two depressions 106, 106" of the engaging cam 106 lying respectively in the range a and in the range of B. Thus the claw 3 alternately performs a transport stroke for the Super-8 format and then a transport stroke for the Standard-8 format.

In order to limit the transport to a single film format, magnet 116 is designed to establish one of the two coincident strokes in range a or B, here specifically the engaging stroke which is prevented as the magnet 116 attracts the claw frame 3 to keep the cam disengaged from the cam track 106. At the same time the teeth 110, 111 are held out of the perforations of the film 1. If now for instance a Standard-8 film is to be transported, the pulse generator 117 is switched so that the magnet 116 receives a pulse 118 while the hump a of the transport cam passes the cam follower 5 of FIG; 7. If, on the other hand, the transport of a Super8 film is desired, the phase of the pulse generator is shifted so that a pulse 119 energizes the magnet 1 16 in the operative position of hump b. These humps a and b are correlated with respective light-interrupting phases of the shutter 8, here specifically the phases 8a and 8b.

Instead of inhibiting the engaging stroke it is of course also possible, within the scope of our invention, to arrest the transport stroke, e.g. according to the teaching of commonly owned US. Pat. No. 3,602,41 l to Eduard Keznickl.

Our invention is applicable not only to different film formats, but also to forward and reverse movement.

This has been illustrated in FIGS. 8 and 9 in which equivalent elements again bear the same reference numerals as in other embodiments. FIG. 9 shows the profile of a transport cam 107 whose single hump has a rising flank in the range a, for effecting forward movement, and a falling flank designed for reverse movement in the range B. To each of these two movements there is again assigned one engaging dwell, i.e. a depression 106 or 106", on cam track 106. In contrast to the electric pulse generator according to FIG. 6, there is now provided a mechanical pulse generator in the form of two cams 120, 121 which co-operate with a lever 123 fulcrumed on an axle 122. The free end of the lever 123 abuts the claw frame 3 which comprises, besides the cam follower 5 for the transport stroke, a further cam follower 125 for the engaging stroke. By means of the cam 120 and the transmitting lever 123, the claw frame with its cam follower 124 may be lifted off the engaging cam 106 and the claw tooth 110 may be kept out of the perforations of a film strip. The profile of the control cams 120, 121 is such, as seen in FIG. 9, that the cam prevents the stroke in the range [3 whereas the cam 121 prevents the stroke in the range For the switching of the lever 123 from one control cam to the other, its pivoted axle 122 is shiftable by means of a handle 125, this axle being indexable in either of its two operating positions by means of a detent 126.

As the lever 123 may be made as long as desired, the vicinity of claw frame 3 may be largely kept free from structural members. The space required for the switching of the lever 123 from one mode of operation to the other may be relatively small, as illustrated. The arrangement could also be reversed so that instead of the lever 123 the cams 120, 121 are displaced.

The use of electric pulse generators for changing the stroke length or direction is especially advantageous in a system already provided with means for blocking the transport and/or the engaging stroke for the purpose of changing the feed rate, in which case few structural ad ditions will be needed.

What is claimed is:

1. A strip-feeding mechanism for optical equipment adapted to scan an intermittently advancing film strip provided with a row of longitudinally equispaced perforations, comprising:

a source intermittent intermittent illumination for said film strip interrupted by periodically recurrent off-periods;

first and second cam means mounted for rotation in synchronized relationship with said source for performing a revolution coinciding with a plurality of said off-periods;

guide means for leading a film strip along a predetermined path;

feed means engageable with a perforation of said film strip but normally disengaged therefrom, said feed means being displaceable by said first cam means in a transport direction substantially parallel to said path and being displaceable by said second cam means in a perforation-engaging direction generally transverse to said path, said first cam means being provided with a plurality of transport formations at peripherally spaced locations for coacting with said feed means during different off-periods in the course of a revolution, said second cam means 7 having at least one engaging formation positioned for coacting with said feed means during any of said different off-periods to enable entrainment of said film strip by any one of said transport formations upon engagement of said feed means with a perforation thereof, said transport formations having configurations corresponding to different trans- 3. A mechanism as defined in claim 2 wherein said first cam means comprises a body centered on an axis of rotation generally perpendicular to the plane of said film strip, said feed means comprising a claw carrier swingable about a pivotal axis substantially parallel to said plane and shiftable in the direction of said pivotal axis, said body having at least one peripheral hump with sloping flanks constituting said transport formations, said claw carrier being provided with a cam follower engageable with said flanks for shifting thereby.

4. A mechanism as defined in claim 3 wherein said source includes a shutter provided with a plurality of angularly equispaced vanes interposable in the path of a light beam, said shutter and said body being coaxially mounted for joint rotation, the angular spacing of certain of said vanes equaling the angular spacing of said flanks.

5. A mechanism as defined in claim 3 wherein said second cam means comprises an annular member coaxial with said body and force-transmitting means coacting with a dwell on said member for swinging said carrier in said perforation-engaging direction.

6. A mechanism as defined in claim 5 wherein said member and said force-transmitting means are operatively coupled with said control means for relative angular displacement by a distance corresponding to the angular spacing of said flanks.

7. A mechanism as defined in claim 5 wherein said member forms a plurality of concentric annular cam tracks provided with respective dwells, said forcetransmitting means being displaceable by said control means for selective alignment with any one of said cam tracks.

8. A mechanism as defined in claim 5 wherein said control means comprises an inhibitor selectively synchronizable with said source to block the swinging of said carrier in said all but one of said off-periods.

9. A mechanism as defined in claim 3 wherein said body has a plurality of peripheral humps, said transport formations being similarly sloping flanks of said humps differing in height from one another.

10. A mechanism as defined in claim 3 wherein said 

1. A strip-feeding mechanism for optical equipment adapted to scan an intermittently advancing film strip provided with a row of longitudinally equispaced perforations, comprising: a source intermittent intermittent illumination for said film strip interrupted by periodically recurrent off-periods; first and second cam means mounted for rotation in synchronized relationship with said source for performing a revolution coinciding with a plurality of said off-periods; guide means for leading a film strip along a predetermined path; feed means engageable with a perforation of said film strip but normally disengaged therefrom, said feed means being displaceable by said first cam means in a transport direction substantially parallel to said path and being displaceable by said second cam means in a perforation-engaging direction generally transverse to said path, said first cam means being provided with a plurality of transport formations at peripherally spaced locations for coacting with said feed means during different off-periods in the course of a revolution, said second cam means having at least one engaging formation positioned for coacting with said feed means during any of said different off-periods to enable entrainment of said film strip by any one of said transport formations upon engagement of said feed means with a perforation thereof, said transport formations having configurations corresponding to different transport modes; and control means operatively coupled with one of said cam means for selectively deactivating same during all but one of said offperiods occurring in the course of one revolution.
 2. A mechanism as defined in claim 1 wherein said control meanS is operatively coupled with said second cam means.
 3. A mechanism as defined in claim 2 wherein said first cam means comprises a body centered on an axis of rotation generally perpendicular to the plane of said film strip, said feed means comprising a claw carrier swingable about a pivotal axis substantially parallel to said plane and shiftable in the direction of said pivotal axis, said body having at least one peripheral hump with sloping flanks constituting said transport formations, said claw carrier being provided with a cam follower engageable with said flanks for shifting thereby.
 4. A mechanism as defined in claim 3 wherein said source includes a shutter provided with a plurality of angularly equispaced vanes interposable in the path of a light beam, said shutter and said body being coaxially mounted for joint rotation, the angular spacing of certain of said vanes equaling the angular spacing of said flanks.
 5. A mechanism as defined in claim 3 wherein said second cam means comprises an annular member coaxial with said body and force-transmitting means coacting with a dwell on said member for swinging said carrier in said perforation-engaging direction.
 6. A mechanism as defined in claim 5 wherein said member and said force-transmitting means are operatively coupled with said control means for relative angular displacement by a distance corresponding to the angular spacing of said flanks.
 7. A mechanism as defined in claim 5 wherein said member forms a plurality of concentric annular cam tracks provided with respective dwells, said force-transmitting means being displaceable by said control means for selective alignment with any one of said cam tracks.
 8. A mechanism as defined in claim 5 wherein said control means comprises an inhibitor selectively synchronizable with said source to block the swinging of said carrier in said all but one of said off-periods.
 9. A mechanism as defined in claim 3 wherein said body has a plurality of peripheral humps, said transport formations being similarly sloping flanks of said humps differing in height from one another.
 10. A mechanism as defined in claim 3 wherein said flanks slope in opposite directions. 